In order to meet wireless data traffic demands that have increased after 4th Generation (4G) communication system commercialization, efforts to develop an improved 5G communication system or a pre-5G communication system have been made. For this reason, the 5G communication system or the pre-5G communication system is called a beyond 4G network communication system or a post Long Term Evolution (LTE) system.
In order to achieve a high data transmission rate, an implementation of the 5G communication system in a mm Wave band (for example, 60 GHz band) is being considered. In the 5G communication system, technologies such as beamforming, massive Multi-Input Multi-Output (MIMO), Full Dimensional MIMO (FD-MIMO), array antenna, analog beam-forming, and large scale antenna are discussed to mitigate propagation path loss in the mmWave band and increase propagation transmission distance.
Further, technologies such as an evolved small cell, an advanced small cell, a cloud Radio Access Network (cloud RAN), an ultra-dense network, Device to Device communication (D2D), a wireless backhaul, a moving network, cooperative communication, Coordinated Multi-Points (CoMP), and received interference cancellation to improve the system network have been developed for the 5G communication system.
In addition, the 5G system has developed Advanced Coding Modulation (ACM) schemes such as Hybrid FSK and QAM Modulation (FQAM) and Sliding Window Superposition Coding (SWSC), and advanced access technologies such as Filter Bank Multi Carrier (FBMC), Non Orthogonal Multiple Access (NOMA), and Sparse Code Multiple Access (SCMA).
Meanwhile, the Internet has been evolved to an Internet of Things (IoT) network in which distributed components such as objects exchange and process information from a human-oriented connection network in which humans generate and consume information. Internet of Everything (IoE) technology may be an example of a combination of the IoT technology and big data processing technology through a connection with a cloud server.
In order to implement the IoT, research is being conducted on technical factors such as a sensing technique, wired/wireless communication and network infrastructure, service interface technology, and security technology are required, and thus technologies such as a sensor network, Machine to Machine (M2M), Machine Type Communication (MTC), and the like for a connection between objects.
In an IoT environment, through collection and analysis of data generated in connected objects, an intelligent Internet Technology (IT) service to create a new value for people's lives may be provided. The IoT may be applied to fields, such as a smart home, smart building, smart city, smart car, connected car, smart grid, health care, smart home appliance, or high-tech medical service, through the convergence of the conventional Information Technology (IT) and various industries.
Accordingly, various attempts to apply the 5G communication to the IoT network are made. For example, 5G communication technologies such as a sensor network, Machine to Machine (M2M), and MTC are implemented by the schemes such as beamforming, MIMO, and array antenna. The application of a cloud RAN as the big data processing technology may be an example of convergence of the 5G technology and the IoT technology.
Vehicle-to-Everything (V2X) is another example corresponding to a general term that refers to all types of communication schemes applicable to a means of transportation located on a road, for example, a vehicle and means a specific communication technology for implementing “Connected Vehicle” or “Networked Vehicle”. The V2X networking is divided into three types, that is, Vehicle-to-Infrastructure (V2I) communication, Vehicle-to-Vehicle (V2V) communication, and Vehicle-to-Pedestrian (V2P) communication.
The development of V2I and V2V technology has been conducted with major objectives to improve road safety and, through the incorporation with the development of wireless communication technology, various additional IT services as well as initial safety-related use cases have been considered in recent years. The main advanced countries of telematics/ITS technology such as the EU, North America, Japan, and Korea have verified effectiveness and applicability of the technology through large-scale projects over the years.
According to such a trend, a 3rd Generation Partnership Project (3GPP) group has conducted standardization work to provide V2X communication based on LTE-Advanced. A Service Aspects (SA) group has defined requirements to be achieved in V2X communication as shown in Table 1 below and has agreed with the use of Device-to-Device (D2D) discovery and a communication function applied to the system after LTE Rel-12 for V2V and V2P communication.
TABLE 1requirements in V2X communication based on 3GPP LTE-AdvancedParameterValueLatencyTypically Max. 100 ms(End-to-End)Max. 20 ms for PCSWReliability80~95%Range50~320 meterAbsolute VelocityMax. 160 Km/hRelative VelocityMax. 280 Km/hMessage sizeTypically 50-300 BytesUp to 1200 BytesMessage Frequency10 Messages per second
Further, in V2I communication, communication with a Road-Side-Unit (RSU), which is communication equipment installed on the side of the road by an enhanced Node B (eNB) or a network service provider, is considered. At this time, the RSU may be recognized as one of the eNB and User Equipment (UE) to neighboring vehicles. Accordingly, in the specification, an RSU type in a case where the RSU is recognized as the eNB is defined as an “eNB-Type RSU”, and an RSU type in a case where the RSU is recognized as the UE is defined as a “UE-Type RSU” for the convenience of the description. In V2I communication between the vehicle and the UE-Type RSU, the conventional Device to Device (D2D) discovery and communication function may be used like in V2V and V2P communication. Further, in communication between the eNB or the eNB-Type RSU and the vehicle, the conventional cellular uplink/downlink transmission/reception-based communication technology may be used.
In the above described LTE-based V2X communication, the conventional communication scheme may be re-used, but it is expected that, in order to meet the requirements to achieve V2X communication, some improvements must be made in the conventional communication scheme. Accordingly, a 3GPP Radio Access Network (RAN) group has examined various element technologies for supporting the V2X communication and standard changes in the conventional communication scheme through preceding research in the LTE-Release-13 standardization process. Particularly, the 3GPP RAN group has improved the conventional D2D discovery/communication channel structure and resource allocation method to reduce a response delay (latency) and increase reliability in D2D-based V2X communication and has discussed a method of improving a DeModulation-Reference Signal (DM-RS) allocation structure to increase channel estimation performance in a high speed movement environment.